Device for preparing high-purity oxygen through air separation

Abstract

The utility model relates to a device for preparing high-purity oxygen through air separation. The device comprises an air compressor used for compressing raw material air and a pre-cooling and purifying system used for pre-cooling and purifying the raw material air to obtain purified air. The fractionating tower is used for rectifying the cooled air to be rectified to obtain intermediate gas; the high-purity oxygen tower is used for rectifying the intermediate gas to obtain high-purity liquid oxygen; the high-purity oxygen tower evaporator is arranged at the bottom of the high-purity oxygen tower and is used for liquefying the cooled air into liquid air; the high-purity oxygen tower condenser is arranged at the top of the high-purity oxygen tower and is used for converting the liquid air into evaporated air; and the heat exchange system is used for cooling circulating air formed by converging one part of purified air and backflow air into cooled air, cooling the other part of purified air into cooled air to be rectified, reheating evaporated air into backflow air and reheating high-purity liquid oxygen into high-purity oxygen. The device is simple in structure, convenient to operate, high in efficiency and not limited by raw material sources.

Description

Technical Field

[0001] This utility model relates to the field of gas preparation technology, specifically to an apparatus for producing high-purity oxygen using air separation. Background Technology

[0002] In existing technologies, liquid oxygen and industrial oxygen are often used as raw materials to produce high-purity oxygen. However, this process is relatively complex, inconvenient to operate, has low efficiency, high energy consumption, high investment, and is limited by the availability and geographical location of raw materials. Summary of the Invention

[0003] The purpose of this invention is to provide a device for producing high-purity oxygen through air separation that is simple in structure, easy to control, and highly efficient.

[0004] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0005] An apparatus for producing high-purity oxygen through air separation, comprising:

[0006] An air compressor used to compress raw material air to a specified pressure to form compressed raw material air;

[0007] A pre-cooling and purification system for pre-cooling and purifying compressed raw material air to obtain purified air;

[0008] A distillation column used to distill cooled air to obtain intermediate gases;

[0009] A high-purity oxygen tower used for distilling the intermediate gas to obtain high-purity liquid oxygen;

[0010] The high-purity oxygen tower evaporator is installed at the bottom of the high-purity oxygen tower and is used to liquefy cooled air into liquid air.

[0011] A high-purity oxygen tower condenser is installed at the top of the high-purity oxygen tower and is used to vaporize the liquid air into evaporated air.

[0012] A heat exchange system for reheating the evaporated air into the reflux air, cooling a portion of the purified air and the reflux air to form circulating air into the cooled air, cooling another portion of the purified air into the cooled air to be distilled, and reheating the high-purity liquid oxygen into high-purity oxygen.

[0013] The air compressor has a raw air inlet and a compressed air outlet; the precooling and purification system has an inlet for inputting the raw air and an outlet for outputting the purified air; the fractionation tower has an inlet for inputting the cooled air to be refined and an outlet for outputting the intermediate gas; the high-purity oxygen tower has an inlet for inputting the intermediate gas and an outlet for outputting the high-purity liquid oxygen; the high-purity oxygen tower evaporator has an inlet for inputting the cooled air and an outlet for outputting the liquid air; the high-purity... The oxygen tower condenser has a liquid inlet for inputting the liquid air and an outlet for outputting the evaporated air; the heat exchange system has a first inlet for inputting the circulating air, a first outlet for outputting the cooled air, a second inlet for inputting another portion of the purified air, a second outlet for outputting the cooled air to be refined, a third inlet for inputting the evaporated air, a third outlet for outputting the reflux air, a liquid inlet for inputting the high-purity liquid oxygen, and a fourth outlet for outputting the high-purity oxygen.

[0014] The raw material air inlet of the air compressor is connected to an atmospheric air source, and the compressed air outlet of the air compressor is connected to the air inlet of the pre-cooling purification system.

[0015] The outlet of the precooling purification system is connected to the first inlet and the second inlet of the heat exchange system, respectively.

[0016] The first outlet of the heat exchange system is connected to the inlet of the high-purity oxygen tower evaporator, and the second outlet of the heat exchange system is connected to the inlet of the fractionation tower.

[0017] The gas outlet of the fractionation tower is connected to the gas inlet of the high-purity oxygen tower, and the liquid outlet of the high-purity oxygen tower is connected to the liquid inlet of the heat exchange system.

[0018] The fourth outlet of the heat exchange system is connected to a high-purity oxygen storage tank or a high-purity oxygen application device. The liquid outlet of the high-purity oxygen tower evaporator is connected to the liquid inlet of the high-purity oxygen tower condenser. The gas outlet of the high-purity oxygen tower condenser is connected to the third inlet of the heat exchange system. The third outlet of the heat exchange system is connected to the first inlet of the heat exchange system.

[0019] The fractionation column includes a lower column, an upper column, and a main condenser-evaporator disposed at the bottom of the upper column. The gas inlet of the fractionation column is located at the lower part of the lower column, and the gas outlet of the fractionation column is located at the middle part of the upper column. The lower column has a liquid air outlet for outputting liquid air, a nitrogen outlet for outputting nitrogen gas, and a liquid nitrogen inlet for inputting liquid nitrogen. The upper column has a liquid air inlet for inputting liquid air, a nitrogen outlet for outputting nitrogen gas, a liquid nitrogen inlet for inputting liquid nitrogen, a waste nitrogen outlet for outputting waste nitrogen gas, and a liquid oxygen outlet for outputting liquid oxygen. The main condenser-evaporator has a nitrogen inlet for inputting nitrogen gas and a liquid nitrogen outlet for outputting liquid nitrogen gas.

[0020] The liquid air outlet of the lower column is connected to the liquid air inlet of the upper column, the nitrogen outlet of the lower column is connected to the nitrogen inlet of the main condenser-evaporator, the liquid nitrogen outlet of the main condenser-evaporator is connected to the liquid nitrogen inlet of the lower column and the liquid nitrogen inlet of the upper column, respectively, the nitrogen outlet of the upper column is connected to a nitrogen storage tank or a nitrogen application device via the heat exchange system, and the waste nitrogen outlet and the liquid oxygen outlet of the upper column are both connected to a waste nitrogen storage tank or a waste nitrogen application device via the heat exchange system.

[0021] The high-purity oxygen tower also has an outlet for discharging waste gas and an inlet for inputting waste liquid; the high-purity oxygen tower condenser also has an inlet for inputting waste gas, an outlet for discharging the waste gas, and an outlet for discharging waste liquid; the outlet of the high-purity oxygen tower is connected to the inlet of the high-purity oxygen tower condenser, the outlet of the high-purity oxygen tower condenser is connected to the inlet of the high-purity oxygen tower, and the outlet of the high-purity oxygen tower condenser is connected to a waste nitrogen storage tank or a waste nitrogen application device via the heat exchange system.

[0022] The heat exchange system includes a main heat exchanger, a turboexpander, and a cooler. The main heat exchanger has a first cooling channel, a first reheating channel, and a second reheating channel. The two ends of the first cooling channel form a second air inlet and a second air outlet of the heat exchange system. The two ends of the first reheating channel form a third air inlet and a third air outlet of the heat exchange system. The two ends of the second reheating channel form a liquid inlet and a fourth air outlet of the heat exchange system. The main heat exchanger also has a second cooling channel and a third cooling channel. The input end of the second cooling channel of the main heat exchanger is connected to the input end of the booster end of the turbine expander to form the first air inlet of the heat exchange system. The output end of the second cooling channel of the main heat exchanger is connected to the input end of the expansion end of the turbine expander. The output end of the booster end of the turbine expander is connected to the input end of the cooler. The output end of the cooler is connected to the input end of the third cooling channel of the main heat exchanger. The output end of the third cooling channel of the main heat exchanger and the output end of the expansion end of the turbine expander are connected to form the first output end of the heat exchange system.

[0023] The main heat exchanger also has a third reheating channel and a fourth reheating channel. The nitrogen outlet of the upper column is connected to the input end of the third reheating channel of the main heat exchanger. The output end of the third reheating channel of the main heat exchanger is connected to the nitrogen storage tank or nitrogen application device. The waste nitrogen outlet of the upper column and the liquid oxygen outlet of the upper column are connected together and then connected to the input end of the fourth reheating channel of the main heat exchanger. The output end of the fourth reheating channel of the main heat exchanger is connected to the waste nitrogen storage tank or waste nitrogen application device.

[0024] The heat exchange system also includes a circulating air compressor. The first air inlet of the heat exchange system is connected to the input end of the circulating air compressor, and the output end of the circulating air compressor is connected to the input end of the second cooling channel of the main heat exchanger and the input end of the booster end of the turbine expander.

[0025] The heat exchange system further includes a liquid air-liquid nitrogen subcooler, which has a first subcooling channel, a second subcooling channel, a first reheating channel, and a second reheating channel. The nitrogen outlet of the upper column is connected to the input end of the third reheating channel of the main heat exchanger via the first reheating channel of the liquid air-liquid nitrogen subcooler. The waste nitrogen outlet of the upper column is connected to the liquid oxygen outlet of the upper column via the second reheating channel of the liquid air-liquid nitrogen subcooler and then connected to the input end of the fourth reheating channel of the main heat exchanger. The liquid air outlet of the lower column is connected to the liquid air inlet of the upper column via the first subcooling channel of the liquid air-liquid nitrogen subcooler. The liquid nitrogen outlet of the main condenser-evaporator is connected to the liquid nitrogen inlet of the upper column via the second subcooling channel of the liquid air-liquid nitrogen subcooler.

[0026] The heat exchange system also includes a liquid-air subcooler, which has a subcooling channel and a reheating channel. The outlet of the high-purity oxygen tower condenser is connected to the third inlet of the heat exchange system via the reheating channel of the liquid-air subcooler. The liquid outlet of the high-purity oxygen tower evaporator is connected to the liquid inlet of the high-purity oxygen tower condenser via the subcooling channel of the liquid-air subcooler.

[0027] The air separation device for producing high-purity oxygen also includes a high-purity oxygen pump. The liquid outlet of the high-purity oxygen tower is connected to the input of the high-purity oxygen pump, and the output of the high-purity oxygen pump is connected to the liquid inlet of the heat exchange system.

[0028] A high-purity liquid oxygen branch is provided between the output end of the high-purity oxygen pump and the inlet end of the heat exchange system for outputting high-purity liquid oxygen.

[0029] Due to the application of the above technical solution, this utility model has the following advantages compared with the prior art: this utility model has a simple structure, is easy to operate, has high efficiency, and is not limited by raw materials. Attached Figure Description

[0030] Appendix Figure 1 This is a schematic diagram of the apparatus for producing high-purity oxygen by air separation according to this utility model. Detailed Implementation

[0031] The present invention will be further described below with reference to the embodiments shown in the accompanying drawings.

[0032] Example 1: As shown in the attached document Figure 1 As shown, an apparatus for producing high-purity oxygen by air separation includes an air compressor, a pre-cooling purification system, a fractionation tower, a high-purity oxygen tower C3, a high-purity oxygen tower evaporator K3, a high-purity oxygen tower condenser K2, a heat exchange system, and a high-purity oxygen pump OP.

[0033] An air compressor is used to compress raw air to a specified pressure to form compressed raw air. It has a raw air inlet and a compressed air outlet. The raw air inlet of the air compressor is connected to an atmospheric air source, and the compressed air outlet of the air compressor is connected to a pre-cooling and purification system.

[0034] The precooling and purification system is used to precool and purify the compressed raw air to obtain purified air. The fractionation column is used to distill the cooled air to obtain intermediate gases. The high-purity oxygen column C3 is used to distill the intermediate gases to obtain high-purity liquid oxygen. The high-purity oxygen column evaporator K3 is located at the bottom of the high-purity oxygen column C3 to liquefy the cooled air into liquid air. The high-purity oxygen column condenser K2 is located at the top of the high-purity oxygen column C3 to condense the liquid air into evaporated air. The heat exchange system is located between the precooling and purification system, the fractionation column, the high-purity oxygen column C3, the high-purity oxygen column evaporator K3, and the high-purity oxygen column condenser K2. It is used to cool a portion of the purified air and the reflux air to form the circulating air, cool another portion of the purified air to form the cooled air to be distilled, reheat the evaporated air to reflux air, and reheat the high-purity liquid oxygen to high-purity oxygen.

[0035] The precooling and purification system has an inlet for inputting raw air and an outlet for outputting purified air. The fractionation column has an inlet for inputting cooled air to be refined and an outlet for outputting intermediate gases. The high-purity oxygen column C3 has an inlet for inputting intermediate gases and an outlet for outputting high-purity liquid oxygen. The high-purity oxygen column evaporator K3 has an inlet for inputting cooled air and an outlet for outputting liquid air. The high-purity oxygen column condenser K2 has an inlet for inputting liquid air and an outlet for outputting evaporated air. The heat exchange system has a first inlet for inputting circulating air, a first outlet for outputting cooled air, a second inlet for inputting another portion of purified air, a second outlet for outputting cooled air to be refined, a third inlet for inputting evaporated air, a third outlet for outputting reflux air, an inlet for inputting high-purity liquid oxygen, and a fourth outlet for outputting high-purity oxygen.

[0036] The inlet of the precooling and purification system is connected to the compressed air outlet of the air compressor. The outlet of the precooling and purification system is connected to the first and second inlets of the heat exchange system. The first outlet of the heat exchange system is connected to the inlet of the high-purity oxygen tower evaporator K3. The second outlet of the heat exchange system is connected to the inlet of the fractionation tower. The outlet of the fractionation tower is connected to the inlet of the high-purity oxygen tower C3. The liquid outlet of the high-purity oxygen tower C3 is connected to the liquid inlet of the heat exchange system. The fourth outlet of the heat exchange system is connected to the high-purity oxygen storage tank or the high-purity oxygen application device for outputting high-purity oxygen. The liquid outlet of the high-purity oxygen tower evaporator K3 is connected to the liquid inlet of the high-purity oxygen tower condenser K2. The outlet of the high-purity oxygen tower condenser K2 is connected to the third inlet of the heat exchange system. The third outlet of the heat exchange system is connected to the first inlet of the heat exchange system.

[0037] The more specific structure of the above-mentioned air separation device for producing high-purity oxygen is as follows:

[0038] The fractionation column includes a lower column C1, an upper column C2, and a main condenser-evaporator K1, which is located at the bottom of the upper column C2. The gas inlet of the fractionation column is located at the lower part of the lower column C1, and the gas outlet of the fractionation column is located in the middle of the upper column C2. The lower column C1 also has a liquid air outlet for discharging liquid air, a nitrogen outlet for discharging nitrogen gas, and a liquid nitrogen inlet for inputting liquid nitrogen. The upper column C2 also has a liquid air inlet for inputting liquid air, a nitrogen outlet for discharging nitrogen gas, a liquid nitrogen inlet for inputting liquid nitrogen, a waste nitrogen outlet for discharging waste nitrogen gas, and a liquid oxygen outlet for discharging liquid oxygen gas. The main condenser-evaporator K1 has a nitrogen inlet for inputting nitrogen gas and a liquid nitrogen outlet for discharging liquid nitrogen gas. The liquid air outlet of the lower column C1 is connected to the liquid air inlet of the upper column C2. The nitrogen outlet of the lower column C1 is connected to the nitrogen inlet of the main condenser-evaporator K1. The liquid nitrogen outlet of the main condenser-evaporator K1 is connected to the liquid nitrogen inlet of the lower column C1 and the liquid nitrogen inlet of the upper column C2. The nitrogen outlet of the upper column C2 is connected to a nitrogen storage tank or a nitrogen application device via a heat exchange system for outputting nitrogen. The waste nitrogen outlet and the liquid oxygen outlet of the upper column C2 are connected to a waste nitrogen storage tank or a waste nitrogen application device via a heat exchange system.

[0039] The high-purity oxygen tower C3 also has an outlet for discharging waste gas and an inlet for inputting waste liquid. The high-purity oxygen tower condenser K2 also has an inlet for inputting waste gas, an outlet for discharging waste gas, and an outlet for discharging waste liquid. The outlet of the high-purity oxygen tower C3 is connected to the inlet of the high-purity oxygen tower condenser K2, and the outlet of the high-purity oxygen tower condenser K2 is connected to the inlet of the high-purity oxygen tower C3. The waste gas outlet of the high-purity oxygen tower condenser K2 is connected to a waste nitrogen storage tank or waste nitrogen application device via a heat exchange system for discharging waste nitrogen.

[0040] The heat exchange system includes a main heat exchanger E1, a turboexpander ET, and a cooler WE1. The main heat exchanger E1 has a first cooling channel, a first reheating channel, and a second reheating channel. The two ends of the first cooling channel of the main heat exchanger E1 form the second air inlet and the second air outlet of the heat exchange system. The two ends of the first reheating channel of the main heat exchanger E1 form the third air inlet and the third air outlet of the heat exchange system. The two ends of the second reheating channel of the main heat exchanger E1 form the liquid inlet and the fourth air outlet of the heat exchange system. The main heat exchanger E1 also has a second cooling channel and a third cooling channel. The input end of the second cooling channel of the main heat exchanger E1 is connected to the input end of the booster end of the turbine expander ET to form the first air inlet of the heat exchange system. The output end of the second cooling channel of the main heat exchanger E1 is connected to the input end of the expansion end of the turbine expander ET. The output end of the booster end of the turbine expander ET is connected to the input end of the cooler WE1. The output end of the cooler WE1 is connected to the input end of the third cooling channel of the main heat exchanger E1. The output end of the third cooling channel of the main heat exchanger E1 is connected to the output end of the expansion end of the turbine expander ET to form the first output end of the heat exchange system.

[0041] The main heat exchanger E1 also has a third reheating channel and a fourth reheating channel. The nitrogen outlet of the upper column C2 is connected to the input end of the third reheating channel of the main heat exchanger E1, and the output end of the third reheating channel of the main heat exchanger E1 is connected to a nitrogen storage tank or a nitrogen application device. The waste nitrogen outlet of the upper column C2 and the liquid oxygen outlet of the upper column C2 are connected together and then connected to the input end of the fourth reheating channel of the main heat exchanger E1, and the output end of the fourth reheating channel of the main heat exchanger E1 is connected to a waste nitrogen storage tank or a waste nitrogen application device.

[0042] The heat exchange system also includes a circulating air compressor RC. The first air inlet of the heat exchange system is connected to the input of the circulating air compressor RC, and the output of the circulating air compressor RC is connected to the input of the second cooling channel of the main heat exchanger E1 and the input of the booster end of the turbine expander ET.

[0043] The heat exchange system also includes a liquid air-liquid nitrogen subcooler E3, which has a first subcooling channel, a second subcooling channel, a first reheating channel, and a second reheating channel. The nitrogen outlet of the upper column C2 is connected to the input end of the third reheating channel of the main heat exchanger E1 via the first reheating channel of the liquid air-liquid nitrogen subcooler E3. The waste nitrogen outlet of the upper column C2 is connected to the liquid oxygen outlet of the upper column C2 via the second reheating channel of the liquid air-liquid nitrogen subcooler E3 and then to the input end of the fourth reheating channel of the main heat exchanger E1. The liquid air outlet of the lower column C1 is connected to the liquid air inlet of the upper column C2 via the first subcooling channel of the liquid air-liquid nitrogen subcooler E3. The liquid nitrogen outlet of the main condenser-evaporator K1 is connected to the liquid nitrogen inlet of the upper column C2 via the second subcooling channel of the liquid air-liquid nitrogen subcooler E3.

[0044] The heat exchange system also includes a liquid-air subcooler E2, which has a subcooling channel and a reheating channel. The outlet of the high-purity oxygen tower condenser K2 is connected to the third inlet of the heat exchange system via the reheating channel of the liquid-air subcooler E2, and the liquid outlet of the high-purity oxygen tower evaporator K3 is connected to the liquid inlet of the high-purity oxygen tower condenser K2 via the subcooling channel of the liquid-air subcooler E2.

[0045] The outlet of the high-purity oxygen tower C3 is connected to the input of the high-purity oxygen pump OP, and the output of the high-purity oxygen pump OP is connected to the inlet of the heat exchange system. A high-purity liquid oxygen branch is provided between the output of the high-purity oxygen pump OP and the inlet of the heat exchange system for outputting high-purity liquid oxygen.

[0046] The expansion ends of the main heat exchanger E1, the fractionation tower (including the lower tower C1, the upper tower C2 and the main condenser-evaporator K1), the liquid air-liquid nitrogen subcooler E3, the liquid air subcooler E2, the high-purity oxygen tower C3, the high-purity oxygen tower evaporator K3, the high-purity oxygen tower condenser K2, the high-purity oxygen pump OP, and the turbine expander ET are all located in the cold box.

[0047] The method for producing high-purity oxygen using the aforementioned air separation apparatus is as follows:

[0048] The raw air is pre-cooled and purified by a pre-cooling and purification system to obtain purified air. The purified air is then split into two streams. One stream enters the main heat exchanger E1, where it is cooled by the return gas and then sent to the lower tower C1. The other stream merges with the return air output from the main heat exchanger E1 and enters the circulating air compressor RC. The circulating air is pressurized to a certain pressure by the compressor RC to become circulating air. The circulating air is also split into two streams. One stream enters the main heat exchanger E1, where it is cooled to a certain temperature by the return gas and then expands at the expansion end of the turbine expander ET. The other stream enters the pressurization end of the turbine expander ET, where it is pressurized and cooled before also entering the main heat exchanger E1 to be cooled to a certain temperature. After being throttled by a valve, it merges with the expanded air to become cooled air. This cooled air then enters the high-purity oxygen tower evaporator K3, where it condenses into liquid air. The liquid air, after being subcooled in the liquid air subcooler E2, is throttled into the high-purity oxygen tower condenser K2. In the high-purity oxygen tower condenser K2, it evaporates into evaporated air. This evaporated air is then reheated by the liquid air subcooler E2 and the main heat exchanger E1, becoming reflux air. It then merges with another stream of purified air to form circulating air, which enters the circulating air compressor RC for recirculation. The cooled air to be refined enters the lower column C1. After refinement, liquid air is obtained at the bottom of the lower column C1, and nitrogen is obtained at the top. The liquid air, after being subcooled in the liquid air-liquid nitrogen subcooler E3, is throttled into the upper column C2. The nitrogen is condensed into liquid nitrogen in the main condenser-evaporator K1. Part of the liquid nitrogen is used as reflux liquid in the lower column C1 for refinement, while the other part is subcooled in the liquid air-liquid nitrogen subcooler E3 and throttled into the upper column C2. After refinement, the liquid air and liquid nitrogen entering the upper column C2 produce nitrogen at the top of the upper column C2, and contaminated nitrogen is obtained in the upper part of the upper column C2. Nitrogen gas and waste nitrogen gas are reheated in the liquid air-liquid nitrogen subcooler E3 and the main heat exchanger E1, respectively, before being sent out. Liquid oxygen obtained from the bottom of the upper column C2 is extracted and merged with the waste nitrogen gas into the liquid air-liquid nitrogen subcooler E3. In the lower part of the upper column C2, an intermediate gas is extracted and sent to the high-purity oxygen column C3. High-purity liquid oxygen is obtained at the bottom of the high-purity oxygen column C3, and the distillation waste gas is discharged from the top of the high-purity oxygen column C3. The high-purity liquid oxygen is pressurized by the high-purity oxygen pump OP and then vaporized and reheated in the main heat exchanger E1 before being sent out. The waste gas passes through the high-purity oxygen column condenser K2 and is then combined with the waste nitrogen gas output from the upper column C2 before being sent out. The waste liquid (a liquid containing oxygen-rich components with impurities) in the high-purity oxygen column condenser K2 is returned to the high-purity oxygen column C3. An excess of high-purity liquid oxygen product can be extracted after the high-purity oxygen pump OP.

[0049] The above embodiments are only for illustrating the technical concept and features of this utility model, and are intended to enable those skilled in the art to understand the content of this utility model and implement it accordingly. They should not be construed as limiting the scope of protection of this utility model. All equivalent changes or modifications made in accordance with the spirit and essence of this utility model should be included within the scope of protection of this utility model.

Claims

1. An apparatus for producing high-purity oxygen through air separation, characterized in that: The apparatus for producing high-purity oxygen through air separation includes: An air compressor used to compress raw material air to a specified pressure to form compressed raw material air; A pre-cooling and purification system for pre-cooling and purifying compressed raw material air to obtain purified air; A distillation column used to distill cooled air to obtain intermediate gases; A high-purity oxygen tower used for distilling the intermediate gas to obtain high-purity liquid oxygen; The high-purity oxygen tower evaporator is installed at the bottom of the high-purity oxygen tower and is used to liquefy cooled air into liquid air. A high-purity oxygen tower condenser is installed at the top of the high-purity oxygen tower and is used to vaporize the liquid air into evaporated air. A heat exchange system for reheating the evaporated air into reflux air, cooling a portion of the purified air and the reflux air to form circulating air into cooled air, cooling another portion of the purified air into cooled air to be distilled, and reheating the high-purity liquid oxygen into high-purity oxygen. The air compressor has a raw air inlet and a compressed air outlet; the precooling and purification system has an inlet for inputting the raw air and an outlet for outputting the purified air; the fractionation tower has an inlet for inputting the cooled air to be refined and an outlet for outputting the intermediate gas; the high-purity oxygen tower has an inlet for inputting the intermediate gas and an outlet for outputting the high-purity liquid oxygen; the high-purity oxygen tower evaporator has an inlet for inputting the cooled air and an outlet for outputting the liquid air; the high-purity... The oxygen tower condenser has a liquid inlet for inputting the liquid air and an outlet for outputting the evaporated air; the heat exchange system has a first inlet for inputting the circulating air, a first outlet for outputting the cooled air, a second inlet for inputting another portion of the purified air, a second outlet for outputting the cooled air to be refined, a third inlet for inputting the evaporated air, a third outlet for outputting the reflux air, a liquid inlet for inputting the high-purity liquid oxygen, and a fourth outlet for outputting the high-purity oxygen. The raw material air inlet of the air compressor is connected to an atmospheric air source, and the compressed air outlet of the air compressor is connected to the air inlet of the pre-cooling purification system. The outlet of the precooling purification system is connected to the first inlet and the second inlet of the heat exchange system, respectively. The first outlet of the heat exchange system is connected to the inlet of the high-purity oxygen tower evaporator, and the second outlet of the heat exchange system is connected to the inlet of the fractionation tower. The gas outlet of the fractionation tower is connected to the gas inlet of the high-purity oxygen tower, and the liquid outlet of the high-purity oxygen tower is connected to the liquid inlet of the heat exchange system. The fourth outlet of the heat exchange system is connected to a high-purity oxygen storage tank or a high-purity oxygen application device. The liquid outlet of the high-purity oxygen tower evaporator is connected to the liquid inlet of the high-purity oxygen tower condenser. The gas outlet of the high-purity oxygen tower condenser is connected to the third inlet of the heat exchange system. The third outlet of the heat exchange system is connected to the first inlet of the heat exchange system.

2. The apparatus for producing high-purity oxygen by air separation according to claim 1, characterized in that: The fractionation column includes a lower column, an upper column, and a main condenser-evaporator disposed at the bottom of the upper column. The gas inlet of the fractionation column is located at the lower part of the lower column, and the gas outlet of the fractionation column is located at the middle part of the upper column. The lower column has a liquid air outlet for outputting liquid air, a nitrogen outlet for outputting nitrogen gas, and a liquid nitrogen inlet for inputting liquid nitrogen. The upper column has a liquid air inlet for inputting liquid air, a nitrogen outlet for outputting nitrogen gas, a liquid nitrogen inlet for inputting liquid nitrogen, a waste nitrogen outlet for outputting waste nitrogen gas, and a liquid oxygen outlet for outputting liquid oxygen. The main condenser-evaporator has a nitrogen inlet for inputting nitrogen gas and a liquid nitrogen outlet for outputting liquid nitrogen gas. The liquid air outlet of the lower column is connected to the liquid air inlet of the upper column, the nitrogen outlet of the lower column is connected to the nitrogen inlet of the main condenser-evaporator, the liquid nitrogen outlet of the main condenser-evaporator is connected to the liquid nitrogen inlet of the lower column and the liquid nitrogen inlet of the upper column, respectively, the nitrogen outlet of the upper column is connected to a nitrogen storage tank or a nitrogen application device via the heat exchange system, and the waste nitrogen outlet and the liquid oxygen outlet of the upper column are both connected to a waste nitrogen storage tank or a waste nitrogen application device via the heat exchange system.

3. The apparatus for producing high-purity oxygen by air separation according to claim 2, characterized in that: The high-purity oxygen tower also has an outlet for discharging waste gas and an inlet for inputting waste liquid; the high-purity oxygen tower condenser also has an inlet for inputting waste gas, an outlet for discharging the waste gas, and an outlet for discharging waste liquid; the outlet of the high-purity oxygen tower is connected to the inlet of the high-purity oxygen tower condenser, the outlet of the high-purity oxygen tower condenser is connected to the inlet of the high-purity oxygen tower, and the outlet of the high-purity oxygen tower condenser is connected to a waste nitrogen storage tank or a waste nitrogen application device via the heat exchange system.

4. The apparatus for producing high-purity oxygen by air separation according to claim 3, characterized in that: The heat exchange system includes a main heat exchanger, a turboexpander, and a cooler. The main heat exchanger has a first cooling channel, a first reheating channel, and a second reheating channel. The two ends of the first cooling channel form a second air inlet and a second air outlet of the heat exchange system. The two ends of the first reheating channel form a third air inlet and a third air outlet of the heat exchange system. The two ends of the second reheating channel form a liquid inlet and a fourth air outlet of the heat exchange system. The main heat exchanger also has a second cooling channel and a third cooling channel. The input end of the second cooling channel of the main heat exchanger is connected to the input end of the booster end of the turbine expander to form the first air inlet of the heat exchange system. The output end of the second cooling channel of the main heat exchanger is connected to the input end of the expansion end of the turbine expander. The output end of the booster end of the turbine expander is connected to the input end of the cooler. The output end of the cooler is connected to the input end of the third cooling channel of the main heat exchanger. The output end of the third cooling channel of the main heat exchanger and the output end of the expansion end of the turbine expander are connected to form the first output end of the heat exchange system.

5. The apparatus for producing high-purity oxygen by air separation according to claim 4, characterized in that: The main heat exchanger also has a third reheating channel and a fourth reheating channel. The nitrogen outlet of the upper column is connected to the input end of the third reheating channel of the main heat exchanger. The output end of the third reheating channel of the main heat exchanger is connected to the nitrogen storage tank or nitrogen application device. The waste nitrogen outlet of the upper column and the liquid oxygen outlet of the upper column are connected together and then connected to the input end of the fourth reheating channel of the main heat exchanger. The output end of the fourth reheating channel of the main heat exchanger is connected to the waste nitrogen storage tank or waste nitrogen application device.

6. The apparatus for producing high-purity oxygen by air separation according to claim 4, characterized in that: The heat exchange system also includes a circulating air compressor. The first air inlet of the heat exchange system is connected to the input end of the circulating air compressor, and the output end of the circulating air compressor is connected to the input end of the second cooling channel of the main heat exchanger and the input end of the booster end of the turbine expander.

7. The apparatus for producing high-purity oxygen by air separation according to claim 5, characterized in that: The heat exchange system further includes a liquid air-liquid nitrogen subcooler, which has a first subcooling channel, a second subcooling channel, a first reheating channel, and a second reheating channel. The nitrogen outlet of the upper column is connected to the input end of the third reheating channel of the main heat exchanger via the first reheating channel of the liquid air-liquid nitrogen subcooler. The waste nitrogen outlet of the upper column is connected to the liquid oxygen outlet of the upper column via the second reheating channel of the liquid air-liquid nitrogen subcooler and then connected to the input end of the fourth reheating channel of the main heat exchanger. The liquid air outlet of the lower column is connected to the liquid air inlet of the upper column via the first subcooling channel of the liquid air-liquid nitrogen subcooler. The liquid nitrogen outlet of the main condenser-evaporator is connected to the liquid nitrogen inlet of the upper column via the second subcooling channel of the liquid air-liquid nitrogen subcooler.

8. The apparatus for producing high-purity oxygen by air separation according to claim 4, characterized in that: The heat exchange system also includes a liquid-air subcooler, which has a subcooling channel and a reheating channel. The outlet of the high-purity oxygen tower condenser is connected to the third inlet of the heat exchange system via the reheating channel of the liquid-air subcooler. The liquid outlet of the high-purity oxygen tower evaporator is connected to the liquid inlet of the high-purity oxygen tower condenser via the subcooling channel of the liquid-air subcooler.

9. The apparatus for producing high-purity oxygen by air separation according to claim 1, characterized in that: The air separation device for producing high-purity oxygen also includes a high-purity oxygen pump. The liquid outlet of the high-purity oxygen tower is connected to the input of the high-purity oxygen pump, and the output of the high-purity oxygen pump is connected to the liquid inlet of the heat exchange system.

10. The apparatus for producing high-purity oxygen by air separation according to claim 9, characterized in that: A high-purity liquid oxygen branch is provided between the output end of the high-purity oxygen pump and the inlet end of the heat exchange system for outputting high-purity liquid oxygen.

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